You might have a point regarding the end-game content, nonoe really klnows yet. AN have said that they've not fully shared their plans yet, so we'll have to wait and see.
Regarding the combat, you have ten abilities, 5 weapon dependent (or attunement for elementalist), a healing spell, 3 utility spells and an elite spell. And you will use all 10, all of the time, in addition, I have been told that you'll frequently want to swap weapons, to have another 5 at your disposal, giving 15. There are certainly more abilities in a WoW spellbook, but how many classes use more than 10 of them in a fight? On my mage I usually only have to use 4/5, when it comes to PvE.